This invention relates the bonding of an element comprising sapphire, ruby or blue sapphire to another element of such material and relates particularly to the use of a eutectic mixture of aluminum oxide and zirconium oxide to bond such elements to each other. Specifically, the instant inventive concepts relate to the formation of an article such as a sapphire rubidium maser cell with a eutectic bonding agent, although similar concepts can be used for the formation of various articles from such materials such as thermionic convertors, vacuum tubes, high temperature sapphire lamp bulbs and the like.
Particular problems exist in bonding of sapphire to sapphire to form a closed cell that can be outgassed at a high temperature, evacuated and filled with rubidium vapor as in the formation of a sapphire rubidium maser cell. The cell must be vacuum tight after sealing and non-reactive to the rubidium vapor. Sapphire has such a narrow temperature range between solid and liquid, only 1.degree. C., that it is impractical to bond sapphire to sapphire directly.
Most bonding heretofore has been done at low temperature with cementitious materials or at elevated temperatures with the use of metalizers and brazing techniques or by the use of graded glass sealing techniques. Most metals and glass outgas at high temperatures in a vacuum or otherwise react with the rubidium vapor thereby contaminating the cell.